Oh, so much this. I've always had hobbies, but the older I get, the more value I get from them. They improve my outlook and quality of life generally, but are also of professional value. Even ones that seem unrelated to development (backpacking, etc) make me a better developer by teaching me new ways of thinking, new skills (it's amazing how many unrelated skills turn out to be more related than it seems), and let me unplug my dev brain and exercise the other parts.
Oh, so much this. I've always had hobbies, but the older I get, the more value I get from them. They improve my outlook and quality of life generally, but are also of professional value. Even ones that seem unrelated to development (backpacking, etc) make me a better developer by teaching me new ways of thinking, new skills (it's amazing how many unrelated skills turn out to be more related than it seems), and let me unplug my dev brain and exercise the other parts.